/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.cors.reactive;

import org.springframework.http.server.PathContainer;
import org.springframework.lang.Nullable;
import org.springframework.web.cors.CorsConfiguration;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.util.pattern.PathPattern;
import org.springframework.web.util.pattern.PathPatternParser;

import java.util.LinkedHashMap;
import java.util.Map;

/**
 * Provide a per reactive request {@link CorsConfiguration} instance based on a
 * collection of {@link CorsConfiguration} mapped on path patterns.
 *
 * <p>Exact path mapping URIs (such as {@code "/admin"}) are supported
 * as well as Ant-style path patterns (such as {@code "/admin/**"}).
 *
 * @author Sebastien Deleuze
 * @author Brian Clozel
 * @since 5.0
 */
public class UrlBasedCorsConfigurationSource implements CorsConfigurationSource {

    private final Map<PathPattern, CorsConfiguration> corsConfigurations;

    private final PathPatternParser patternParser;


    /**
     * Construct a new {@code UrlBasedCorsConfigurationSource} instance with default
     * {@code PathPatternParser}.
     *
     * @since 5.0.6
     */
    public UrlBasedCorsConfigurationSource() {
        this(new PathPatternParser());
    }

    /**
     * Construct a new {@code UrlBasedCorsConfigurationSource} instance from the supplied
     * {@code PathPatternParser}.
     */
    public UrlBasedCorsConfigurationSource(PathPatternParser patternParser) {
        this.corsConfigurations = new LinkedHashMap<>();
        this.patternParser = patternParser;
    }


    /**
     * Set CORS configuration based on URL patterns.
     */
    public void setCorsConfigurations(@Nullable Map<String, CorsConfiguration> corsConfigurations) {
        this.corsConfigurations.clear();
        if (corsConfigurations != null) {
            corsConfigurations.forEach(this::registerCorsConfiguration);
        }
    }

    /**
     * Register a {@link CorsConfiguration} for the specified path pattern.
     */
    public void registerCorsConfiguration(String path, CorsConfiguration config) {
        this.corsConfigurations.put(this.patternParser.parse(path), config);
    }

    @Override
    @Nullable
    public CorsConfiguration getCorsConfiguration(ServerWebExchange exchange) {
        PathContainer lookupPath = exchange.getRequest().getPath().pathWithinApplication();
        return this.corsConfigurations.entrySet().stream()
                .filter(entry -> entry.getKey().matches(lookupPath))
                .map(Map.Entry::getValue)
                .findFirst()
                .orElse(null);
    }

}
